Methodological study to compare the effect of different methods of data collection on the prevalence of self-reported drug use in general population surveys

This report describes the affect of using different survey modes on the measurement of substance use prevalence figures. Three different modes were included in the design of this study: a telephone, a postal, and a face to face survey-mode. The study has been conducted in three European countries: Greece, Sweden and the Netherlands. These countries were selected because they recently conducted a national study on drug use, which laid the foundation for the face-to-face section of this study.